Are Your Patients Getting the Right Form of Quercetin?
Having an absorbable form of quercetin supports the body in many ways: It works as an antioxidant at a cellular level, promotes healthy glucose metabolism, supports healthy circulation, and provides an additional immune system boost.†
Isoquercetin, also known as quercetin-3-monoglucoside, is a type of quercetin that is naturally available in plenty of foods, including apples, onions and grapes. It has a glucoside side chain that is essential for absorption of the quercetin molecule.
Until now, all supplemental forms of quercetin have not had this side chain, and may not have been as effective as you or your patients would hope.
Isoquercetin, an Integrative Therapeutics exclusive, changes that. This supplemental form delivers all the benefits of quercetin with 5 times enhanced bioavailability.†1*
Why Isoquercetin?
Because quercetin – especially when it’s better-absorbed – can support many of the body’s key systems and functions.†
How isoquercetin is absorbed
In the small intestines, enzymes and active transport mechanisms lining the cell walls interact with the glucose, which speeds its uptake and transformation into quercetin.2,3 Without the glucose side chain, absorption occurs through passive diffusion – a much slower and less efficient process.4,5
And, in addition to enhancing bioavailability, the side chain also makes isoquercetin more stable against oxidative damage in the GI tract, too.4
Health benefits
Because isoquercetin is transformed into quercetin in the body, it provides all the health benefits of quercetin in a more bioavailable form.† Quercetin has been shown to prevent the production of free radicals, including reactive oxygen species (ROS) and reactive nitrogen species.†5,6
Research shows that quercetin supports the body’s anti-inflammatory responses.†6 Quercetin also preserves levels of glutathione – one of the body’s own free-radical fighters - during oxidative stress.†7
Immune Response†
The health of your patients’ immune response is a concern any time of year. Quercetin has been studied for its effects on the body’s immune response mechanisms.†6
One way it does this is by inhibiting the degranulation and release of oxidants from mast cells, basophils, and neutrophils.†6,8
Quercetin has also been shown to inhibit the activity of the enzymes tyrosine kinase and nitric oxide synthase and to modulate the immune and inflammatory marker nuclear factor-kappa B (NF-κB), all of which promotes healthy cell regulation.†6,9
In addition, quercetin supports healthy stimulatory signals that play a role in histamine release and inflammation responses.†10
Antioxidant Activity and Cellular Health†
Quercetin is one of the body’s great “recyclers” – one study showed that animals treated with quercetin had higher levels of reduced glutathione and glutathione reductase, which help battle oxidative stress.†7,11 Further research showed that quercetin supported decreased cell proliferation and oxidative damage in the gastric mucosa.†12
Additionally, quercetin supports healthy cellular structure, DNA integrity, and normal cellular apoptosis.†7
Cardiovascular Health†
A diet high in plant polyphenols – including quercetin – has been associated with cardiovascular health in numerous population studies. †7,13
One of the reasons that quercetin ranks so highly as a cardio-supportive ingredient is probably partly due to its support of healthy circulation.†13
For example, in a double-blind, placebo-controlled, crossover study, participants taking 730 mg of quercetin for only 28 days had greater blood pressure support than those taking the placebo.†13
A laboratory study found similar results, concluding that quercetin has important vasorelaxant properties on arteries, supporting healthy circulation.†14
Glucose Metabolism†
Statistically, it’s likely you’ll have patients who need support of healthy glucose metabolism.† Whether this is allied with a concomitant concern about cardiovascular health, or simply exists on its own, isoquercetin may be part of supplement plan for them.†
That’s because quercetin glucosides, such as isoquercetin, have been found to inhibit glucose uptake in the intestines.†15,16 Research suggests that it may be due to competition between quercetin glucosides and glucose via the sodium dependent glucose transporter 1 (SGLT1).†15 This “change-up” or “switch” may slow down the rate of glucose absorption in the body.†17
The potential oxidative damage that sugars can create may also be ameliorated by isoquercetin as well.† It has been studied for its ability to inhibit advanced glycation end-product formation.†18,19 (Glycation is a reaction that combines sugars, fats, and proteins that form compounds the body can’t digest. Advanced glycation end-products may contribute to the overall stress on health.) Similarly, quercetin also supports healthy glucose metabolism by inhibiting aldose reductase, an enzyme that changes glucose to sorbitol.†19
Bringing the right quercetin to your patients
Studies link quercetin to cellular, cardiovascular, and immune system health.†
Isoquercetin from ITI provides the benefits of quercetin to with up to five times better bioavailability than other forms of quercetin.1* That makes it the form the body prefers - and an excellent addition to your patients’ regimens.
*As compared to quercetin-rutinoside
- Hollman PC, Bijsman MN, van Gameren Y, et. al. The sugar moiety is a major determinant of the absorption of dietary flavonoid glycosides in man. Free Radic Res 1999;31(6):569-73.
- Arts IC, Sesink AL, Faassen-Peters M, Hollman PC. The type of sugar moiety is a major determinant of the small intestinal uptake and subsequent biliary excretion of dietary quercetin glycosides. Br J Nutr 2004;91(6):841-7.
- Boyer J, Brown D, Liu RH. In vitro digestion and lactase treatment influence uptake of quercetin and quercetin glucoside by the Caco-2 cell monolayer. Nutr J 2005;4:1
- Morand C, Manach C, Crespy V, Remesy C. Quercetin 3-O-beta-glucoside is better absorbed than other quercetin forms and is not present in rat plasma. Free Radic Res 2000;33(5):667-76.
- Day AJ, Williamson G. Biomarkers for exposure to dietary flavonoids: a review of the current evidence for identification of quercetin glycosides in plasma. Br J Nutr 2001;86 Suppl 1:S105-10.
- Lamson DW, Brignall MS. Antioxidants and cancer, part 3: quercetin. Altern Med Rev 2000;5(3):196-208.
- Fleming T., ed. Quercetin. In: PDR® for Nutritional Supplements. Montvale, NJ: Medical Economics Company; 2001: 390-393.
- Choi YJ, Jeong YJ, Lee YJ, et. al. (-)Epigallocatechin gallate and quercetin enhance survival signaling in response to oxidant-induced human endothelial apoptosis. J Nutr. 2005;135(4):707-13.
- Pearce FL, Befus AD, Bienenstock J. Mucosal mast cells. III. Effect of quercetin and other flavonoids on antigen-induced histamine secretion from rat intestinal mast cells. J Allergy Clin Immunol 1984;73(6):819-23.
- Boots AW, Wilms LC, Swennen EL, et. al. In vitro and ex vivo anti-inflammatory activity of quercetin in healthy volunteers. Nutrition 2008;24(7-8):703-10.
- Senyshyn J, Baumgartner RA, Beaven MA. Quercetin sensitizes RBL-2H3 cells to polybasic mast cell secretagogues through increased expression of Gi GTP-binding proteins linked to a phospholipase C signaling pathway. J Immunol. 1998;160(10):5136-44.
- Ikizler M, Erkasap N, Dernek S, et. al. Dietary polyphenol quercetin protects rat hearts during reperfusion: enhanced antioxidant capacity with chronic treatment. Anadolu Kardiyol Derg. 2007;7(4):404-10.
- Liu JL, Du J, Fan LL, et. al. Effects of quercetin on hyper-proliferation of gastric mucosal cells in rats treated with chronic oral ethanol through the reactive oxygen species-nitric oxide pathway. World J Gastroenterol. 2008;14(20):3242-8.
- Edwards RL, Lyon T, Litwin SE, et. al. Quercetin reduces blood pressure in hypertensive subjects. J Nutr. 2007;137(11):2405-11.
- Duarte J, Pérez-Palencia R, Vargas F, et. al. Antihypertensive effects of the flavonoid quercetin in spontaneously hypertensive rats. Br J Pharmacol. 2001;133(1):117-24.
- Cermak R, Landgraf S, Wolffram S. Quercetin glucosides inhibit glucose uptake into brush-border-membrane vesicles of porcine jejunum. Br J Nutr. 2004 Jun;91(6):849-55.
- Wolffram S, Blöck M, Ader P. Quercetin-3-glucoside is transported by the glucose carrier SGLT1 across the brush border membrane of rat small intestine. J Nutr. 2002;132(4):630-5.
- Ndong M, Uehara M, Katsumata S, Suzuki K. Effects of Oral Administration of Moringa oleifera Lam on Glucose Tolerance in Goto-Kakizaki and Wistar Rats. J Clin Biochem Nutr. 2007;40(3):229-33.
- Kim HY, Moon BH, Lee HJ, Choi DH. Flavonol glycosides from the leaves of Eucommia ulmoides O. with glycation inhibitory activity. J Ethnopharmacol. 2004;93(2-3):227-30.
- Jung HA, Jung YJ, Yoon NY, et. al. Inhibitory effects of Nelumbo nucifera leaves on rat lens aldose reductase, advanced glycation end products formation, and oxidative stress. Food Chem Toxicol. 2008;46(12):3818-26.
Published December 28, 2011